1. Field of the Invention
The field of the present application pertains to medical devices. More particularly, the field of the invention pertains to an apparatus, system, and method for performing surgery.
2. Description of the Related Art
Robotic surgery has many benefits to improve patient recovery time and allows precise control of medical and surgical application instruments. In robotics, an end effector is the device at the “end” of a robotic arm, designed to interact with the environment. As the end effector is the portion of a robot that interacts with the work environment, the exact nature of the end effector depends on the robot's application. For example, several examples of end effectors could include a set of forceps, a pair of scissors, a laser, a camera, a cautery tool, a needle, or any other instrument tip that would benefit from being able to be repositioned.
In the medical field, end effectors may have articulation capabilities that enable them to navigate through anatomical structures in order to reach the operative region. These articulating devices may have bending flexures that comprise a multitude of small moving parts. Typically, these devices present manufacture challenges due to the smaller geometries involved.
In addition to manufacturing challenges relating to the material of the bending flexures themselves, bending flexures in these articulable end effectors often contain a plethora of structures that enable a remote operator to perform the procedure, including pull wires, electrical wires, fluidic lines, and optical fibers. The presence of these components within the bending flexure also impact the device's performance and stability.
FIG. 1 illustrates how components within a bending flexure may be affected by bending moments in the bending flexure. In FIG. 1A, the bending flexure 100, comprising a proximal shaft 101 and distal articulation region 102, is unarticulated. Thus, bending flexure 100 remains perfectly straight, while pull wires 103 and 104 remain lax and of equal length. When unarticulated, bending flexure 100 remains concentric to the neutral axis 105 that runs longitudinally through the length of the bending flexure 100. When unarticulated, the path length of the pull wires 103 and 104 are of equal length within the distal bending flexure 102.
In FIG. 1B, the bending flexure 100 is articulated to the right. Accordingly, within the distal articulation region 102, the path length of pull wire 103 is extended to a distance represented by 106. In contrast, the path length of pull wire 104 is compressed to a distance represented by 107. As a result, the pull wires 103 and 104 exhibit uneven amounts of slack when exiting from the proximal shaft 101. The amount of extension and compression of the path length is proportional to its location relative to the neutral axis 105 in the bending flexure 100. As a rule, path lengths always elongate in the regions further from the direction of articulation, while shortening in paths closer to the direction of articulation.
Developing bending flexures for medical devices also raises a number of design challenges because the ideal articulable end effector is both stiff and bendable, depending on the scenario and required use. For example, when the physician is inserting and driving the end effector into a patient, the device must be relatively stiff in order for the device to pass through and around existing anatomical structures. However, when the physician needs to direct the distal end of the device to reach an operative region, the device is ideally very flexible and bendable. Balancing these design challenges is a constant obstacle for designers.
Existing solutions for bending flexures in small articulable instruments are manufactured using thin-walled tubes, such as hypotubes. Existing manufactures cut intricate patterns into the tubing in order to create reliefs that yield a preferential bending direction. If a large deflection is required; much of the tubing material is removed in order to allow for such bending. The resulting structure, however, is a thin-walled tube with a significant portion of material eliminated, which inevitably loses much of its structure and ability to remain mechanically stable. Especially when the outer diameter of the bending flexure is small, the walls of hypotube do not provide sufficient strength and rigidity when large degree articulations are required and where a surgical tool at the distal end requires rigidity to perform desired procedures.
Therefore, it would be advantageous to have a method and apparatus for facilitating the bending of an instrument with large degrees of articulation while maintaining a sufficient amount of stiffness in order to provide stability at the end effector, all while ensuring ease of manufacturing.